Can fish oil cause atrial fibrillation?

From the Guidelines

Fish oil supplements, particularly at higher doses, may increase the risk of atrial fibrillation in some individuals. According to the most recent and highest quality study, 1, multiple randomized controlled trials of prescription ethyl ester and carboxylic acid preparations of DHA and EPA mixtures and pure EPA as IPE at higher doses (1.8 to 4 g daily) have demonstrated an increase in the risk of AF with therapy. The study highlights that in REDUCE-IT, a larger percentage of patients in the IPE group than in the placebo group were hospitalized for AF or atrial flutter (3.1% vs 2.1%; P = 0.004).

Key points to consider:

• The risk of atrial fibrillation is dose-dependent, with higher doses of omega-3 fatty acids (EPA and DHA) associated with a higher risk of developing this heart rhythm disorder 1.
• People with existing heart conditions or risk factors for atrial fibrillation should be especially cautious when taking fish oil supplements 1.
• Prescription omega-3 fatty acid preparations have been shown to have a higher risk of AF compared to nonprescription fish oil products, likely due to the higher doses and consistent purity of the prescription products 1.
• Consuming fatty fish like salmon or mackerel twice weekly provides omega-3s at levels not typically associated with increased atrial fibrillation risk, offering an alternative for those concerned about this risk but still wanting omega-3 benefits.

It is essential to weigh the potential benefits of fish oil supplements against the potential risks, particularly for individuals with pre-existing heart conditions or risk factors for atrial fibrillation. As supported by the study 1, which found that omega-3 carboxylic acid supplementation was associated with an increased risk of AF in some populations, it is crucial to approach the use of these supplements with caution and under the guidance of a healthcare provider.

From the Research

Fish Oil and Atrial Fibrillation

• The relationship between fish oil and atrial fibrillation is complex, with some studies suggesting that fish oil may reduce the risk of major cardiovascular events, including atrial fibrillation 2, 3, 4, 5.
• However, a recent prospective cohort study found that regular use of fish oil supplements may be a risk factor for atrial fibrillation and stroke among the general population 6.
• The same study found that fish oil supplements may be beneficial for progression of cardiovascular disease from atrial fibrillation to major adverse cardiovascular events, and from atrial fibrillation to death 6.
• The American Heart Association recommends four 3-ounce servings of oily fish weekly, and for those who cannot eat fish or do not have access to fish, capsules of fish oil are readily available in various concentrations 2.
• The recommended doses of eicosapentanoic acid and docosahexanoic acid are in the combined range of 800 to 1000 mg/day for primary and secondary prevention of cardiovascular disease 2, 5.

Key Findings

• Fish oil may have antiarrhythmic effects, which could potentially reduce the risk of atrial fibrillation 2, 3.
• The effects of fish oil on cardiovascular diseases are still being researched, and some studies have yielded inconsistent results 4.
• Regular use of fish oil supplements may have different roles in the transitions from healthy status to atrial fibrillation, to major adverse cardiovascular events, and then to death 6.

Study Limitations

• The studies had different designs, populations, and outcomes, which may limit the comparability of the results 2, 3, 4, 5, 6.
• Further studies are needed to determine the precise mechanisms for the development and prognosis of cardiovascular disease events with regular use of fish oil supplements 6.